Recently, various battery-driven type electronic appliances such as notebook personal computers and portable appliances have been popularized, while the electronic appliances are driven by batteries, or cells. As the batteries for driving these electronic appliances, there are many opportunities that rechargeable batteries, or rechargeable cells (for example, lithium-ion battery) are employed. Then, while a rechargeable battery is repeatedly charged/discharged, battery characteristics thereof (namely, voltage/current characteristics of battery for outputting voltages/currents to load) are different from each other every time this rechargeable battery is charged.
As a consequence, in the case that battery-driven type electronic appliances are tested and/or measured, as previously described, battery characteristics of rechargeable batteries are different from each other every time these rechargeable batteries are charged. As a result, it is difficult to test or measure the electronic appliances in a consistent manner.
Battery characteristic simulating apparatuses are utilized as power supplies instead of rechargeable batteries of electronic appliances. While the battery characteristic simulating apparatuses measure battery characteristics of the rechargeable batteries under a predetermined condition, the battery characteristic simulating apparatuses simulate the measured battery characteristics in a superior reproducibility, and then, supply electric power to the electronic appliances based upon the simulated battery characteristic.
FIG. 5 is a diagram for showing an arrangement of a conventional battery characteristic simulating apparatus.
In FIG. 5, a battery 10 is a battery whose battery characteristic is required to be simulated, and corresponds to, for instance, a lithium-ion battery. Although an electronic appliance 20 is a battery-driven type electronic appliance, the electronic appliance 20 is drivable not only by a battery, but also electric power supplied from an external source (not shown).
A voltage/current curve tracer (will be simply abbreviated as “curve tracer” hereinafter) 30 is provided with a voltage/current generating unit 31, a voltage/current measuring unit 32, a characteristic data storage unit 33, and a communication interface 34, while the curve tracer 30 measures battery characteristics of the battery 10. The voltage/current generating unit 31 and the voltage/current measuring unit 32 are connected to the battery 10. The characteristic data storage unit 33 is connected to the voltage/current generating unit 31 and the voltage/current measuring unit 32 so as to store thereinto characteristic data. The communication interface 34 is communicated with respect to other electronic appliances based upon a predetermined communication protocol.
A general-purpose computer 40 contains another communication interface 41, a calculation unit 42, and a characteristic data table storage unit 43, and is communicated with respect to the curve tracer 30. The communication interface 41 is communicated with the communication interface 34 of the curve tracer 30. The calculation unit 42 is connected to the communication interface 41. The characteristic data storage unit 43 stores thereinto a characteristic data table, and is connected to the calculating unit 42.
A voltage/current generator 50 contains another communication interface 51. The voltage/current generator 50 is communicated with the general-purpose computer 40, and is also connected to the electronic appliance 20. The communication interface 51 of the voltage/current generator 50 is communicated with the communication interface 41 of the general-purpose computer 40.
A voltage/current measuring device 60 contains another communication interface 61, is communicated with the general-purpose computer 40, and is also connected to the electronic appliance 20. The communication interface 61 is communicated with respect to the communication interface 41 of the general-purpose computer 40.
Operations of such a battery characteristic simulating apparatus will now be described. A first description is made of such an operation until a battery characteristic of the battery 10 is acquired.
The voltage/current generating unit 31 of the curve tracer 30 applies a predetermined generated value (namely, outputs either current or voltage) to the battery 10. For instance, the voltage/current generating unit 31 conducts a predetermined current from the battery 10, and at this time, a voltage outputted from the battery 10 is measured by the voltage/current measuring unit 32. Otherwise, the generating unit 31 causes the battery 10 to output a predetermined voltage, and then, at this time, a current outputted from the battery 10 is measured by the measuring unit 32. Then, both the generating unit 31 and the measuring unit 32 store characteristic data of voltage/current constituted by a pair of the generated value and the measured value into the characteristic data storage unit 33.
Furthermore, while the generated value is slightly varied within a predetermined range, plural pieces of characteristic data are measured within the predetermined range, and then, the measured characteristic data are stored in the characteristic data storage unit 33.
When acquisitions of a necessary number of characteristic data are accomplished, the communication interface 34 of the curve tracer 30 is communicated with the communication interface 41 of the general-purpose computer 40 so as to output characteristic data of the characteristic data storage unit 33 to the calculating unit 42 of the general-purpose computer 40.
Thereafter, the calculating unit 42 collects the characteristic data and converts the format of the collected characteristic data into a predetermined format thereof, and then, stores the collected characteristic data having the predetermined format in the table storage unit 43 as a characteristic data table. As a result, the characteristic data table corresponding to the battery characteristic of the battery 10 under predetermined condition is formed in the storage unit 43.
Next, a description is made of operations for outputting to the electronic appliance 20, such output power which simulates a battery characteristic corresponding to the voltage/current characteristic of the battery 10.
An instruction is issued from the calculating unit 42 of the general-purpose computer 40 via the communication interfaces 41 and 51 to the voltage/current generator 50 so as to output therefrom a predetermined generated (either voltage or current). Then, the voltage/current measuring device 60 measures an output of the electronic appliance 20 under the predetermined generated value (namely, if generated value is voltage, then current is measured, whereas if generated value is current, then voltage is measured), and outputs the measured value (either current or voltage value) via the communication interfaces 61 and 41 to the calculating unit 42.
The calculating unit 42 calculates a value (namely, characteristic data) corresponding to the measured value with reference to the characteristic data table of the characteristic data table storage unit 43. In this case, when the corresponding characteristic data is not present in the characteristic data table, the calculating unit 42 interpolates such characteristic data in the vicinity of the measured value in order to obtain the corresponding value. Then, while the calculated value is employed as a new generated value, the calculating unit 42 causes the generator 50 via the communication interfaces 41 and 51 to output a predetermined generated value. Furthermore, the voltage/current measuring device 60 performs a measuring operation for the electronic appliance 50 under the predetermined generated value, and then, outputs a measured value via the communication interfaces 61 and 41 to the calculating unit 42. Since such an operation is repeatedly carried out, the battery characteristic of the battery 10 is reproduced.
[Patent Publication 1]
    JP-A-2003-59544
As previously described, the measured value with respect to the predetermined generated value is acquired, and then the new generated value corresponding to this measured value is calculated. As a result, the battery characteristic can be simulated in higher precision and superior reproducibility.
However, the communication operation is carried out via the communication interfaces 41, 51, and 61 of the respective electronic appliances 40, 50, and 60 every time one generated value is outputted so as to transmit/receive the data. As a consequence, there is such a problem that a lengthy time is required to supply the output in accordance with the battery characteristic to the electronic appliance 20. Also, since such a lengthy time is required, there is another problem that a precise simulation as to the battery characteristic can be hardly carried out.
As a consequence, an object of the present invention is to realize a battery characteristic simulating apparatus for performing an output operation in accordance with a battery characteristic in a high speed.